Microemulsions and Micellar Solutions for Cleaning Wall Painting Surfaces

This paper presents a new approach for the elimination of hydrophobic materials from the surface of wall paintings. Nanostructured systems with well-characterized physicochemical properties are proposed as an alternative to unsupported organic solvents for solubilizing substances on porous painted surfaces. Due to the wide range of components that can be used in their preparation, these systems can potentially be used to remove a wide range of different types of organic materials. The results of experiments using oil-in-water microemulsions and micellar solutions as cleaning agents for wall paintings are given. The efficacy of these systems has been tested in several Italian conservation workshops for the removal of various hydrophobic materials. In particular, they have been successfully used during the conservation of the frescoes in the Loggia del Bigallo in Florence (affected by degraded natural organic materials), and for the removal of various synthetic organic resins from the surface of the Filippo Lippi frescoes in the apse of the Cappella Maggiore in Prato Cathedral. Furthermore, oil-in-water microemulsions have also been shown to be effective cleaning agents for the removal of oil- and acrylic-based paint used by vandals to deface an eighteenth-century a secco painting in the Villa del Barone in Prato. The results are supported by detailed photographic documentation and Fourier transform infrared (FTIR) spectra.